If your 529 plan has the option to send an electronic payment via Ascensus, then you should be able to send your 529 payment to UCSD. Flywire has partnered with Ascensus to send electronic 529 payments to UCSD. Once the funds are received by UCSD, the payment is manually applied to the student account by the Central Cashiers team.
If your 529 plan does not support electronic payments through Ascensus, then you will need to request a paper check to be sent to the TritonPay Office at:
UCSD TritonPay Office
9500 Gilman Drive, MC 0009
La Jolla, CA 92093-0009
If you still have questions or need additional assistance, please submit a ticket.